1. Field of the Invention
This invention relates generally to computer-assisted modeling and planning systems and in particular to a computer-assisted human anatomic and physiologic modeling system used to predict outcomes of medical intervention and further to predict changes in physiologic function under various states, stresses, and environments and still further to generate data for disease research or medical device design.
2. Discussion of Prior Art
Disclosed in Kamm et al., U.S. Pat. No. 6,117,087, is a method and apparatus for deriving a physiological description and clinically-useful data regarding the cardiovascular system of an individual subject. The method includes obtaining a measurement sample associated with cardiovascular flow and utilizing a model, which may be distributed and/or non-linear to derive a description and data. The model generates and uses functions of source parameters and may, in an embodiment, match measurement samples against a library of stored, predicted samples. A best-matching, predicted sample may then be associated with a measurement sample. An apparatus is provided that, according to an embodiment, includes an input for obtaining a measurement sample, a processor to derive the description and data, and an output. The apparatus may also include a digital storage medium to store a library of predicted samples.
Disclosed in Taylor et al., U.S. Pat. No. 6,236,878, is a method for predictive modeling of human anatomy and physiologic function for planning medical interventions on at least one portion of a body with the goals of improving the outcome of the medical intervention and reducing the risks associated with medical intervention. The method comprises the steps of generation of multi-dimensional continuous geometric models of human anatomy, the generation of models of physiologic functions, the integration of the multi-dimensional continuous geometric human anatomy models with the physiologic functional models, and the use of the integrated models to predict the outcome of medical interventions. Also disclosed is a method for the integration of multi-dimensional continuous geometric models of human anatomy and models of physiologic functions to evaluate and predict changes in physiologic function in various functional states, stresses and environments and a method for generating data for disease research.
A method and apparatus for modeling circulation in a living subject is disclosed in Charbel et al, U.S. Pat. No. 7,191,110. The method includes the steps of developing a model for living subjects in general and correcting the model to substantially conform to the overall cerebral physiology of the living subject. The method further includes the step of calculating a cerebral flow of the living subject based upon the corrected model and a selected cerebral blood flow perturbation.
The paper by Spilker et al., Ann Biomed Eng (2007) 35:546-559. DOI 10.1007/s10439-006-9240-3, demonstrates the tuning of a model of pulmonary arterial hemodynamics with morphometry-based impedance outlet boundary conditions. A reduced-order model using steady flow was used to help initialize the tuning of a mean flow fraction and mean pressure of a more detailed model.
The paper by Ellwein et al., Cardiovasc Eng (2008) 8:73-87. DOI 10.1007/s10558-007-9050-8, describes a search for parameter values for unsteady cardiovascular simulations. This work involved tuning lumped-parameter models and, more specifically, models that were reduced to systems of ordinary differential equations (ODE's), which were solved with numerical methods for temporal integration of ODE's. An effort was made to identify the parameters to which the cardiovascular model was most sensitive.
This invention incorporates tuning of reduced-order models of unsteady cardiovascular dynamics and, in addition, reduced-order models that can be solved more quickly using Fourier analysis. In addition, this invention provides the framework for tuning features of time-varying hemodynamic simulations that allows the user to choose either a single objective function that combines many objectives, as in the work of Ellwein et al., or a set of objectives of the same size as the set of parameters so that a solution of a nonlinear system can be sought. This novel use of a limited set of features of the hemodynamic simulations as objectives can give the user control over the most important aspects of the simulation and may save computational energy.
A key difference between this invention and Kamm et al. U.S. Pat. No. 6,117,087, Taylor et al. U.S. Pat. No. 6,236,878, Charbel et al. U.S. Pat. No. 7,191,110, and the work of Ellwein et al. is this invention's use of these less detailed models in the process of tuning hemodynamic simulations that are significantly more computationally expensive. This difference makes this invention most valuable when implemented in software for modeling blood flow in three dimensions for the purposes of intervention planning, disease research and medical device design and evaluation. Previous work does not describe time-varying hemodynamic models of various degrees of complexity and their connection to one another. This aspect of this invention, along with the automation of the tuning process, will save users and computers significant time and effort.